Confessions of a Ragweed Grower: Allergies in the Garden

I am lucky enough not to have any allergies. Zero. Nada. My nose never runs in the spring, my eyes don’t itch in the summer, and I can roll around in a field without fear of anything other than ticks. The only exception? Skin irritation when I battle with brambles. But that’s more a question of thorns than allergies!

This immunity has actually played a trick on me. Unaware of the symptoms that afflict allergy sufferers every summer, I once kept a nasty plant in my garden. Elegant, with its finely cut leaves like lace, I thought it was rather pretty when I saw it sprouting spontaneously at the corner of my house. So much so that I let it grow… Until one day, a friend, with red eyes and a runny nose, told me that I had ragweed all around my patio…

Oops!

I, who had never had to identify it, had unwittingly cultivated the public enemy number one of people suffering from allergies!

Why You and Not Me?

Our immune system is fascinating. Its mission? To defend us against intruders. Except that sometimes it gets a little overzealous. Like my dog, who thinks he’s a guard dog and barks not only at burglars, but also at squirrels, the wind rustling my greenhouse, and even the shadows of leaves… Believe me, I feel VERY well protected at home!

Allergies are exactly the same: your immune system mistakes harmless pollen for a dangerous invader. The first time it encounters the allergen, nothing visible happens, but the body produces antibodies. It’s like taking photos and putting together an album of “wanted suspects.” Then, upon subsequent contact, these antibodies recognize the intruder and trigger a cascade of reactions, including the release of histamine—responsible for the symptoms we all know: sneezing, runny nose, itchy eyes… Except that with an overzealous immune system, we don’t feel as protected as we do with my guard dogs!

But why are some people allergic to ragweed and others to birch? Why does your neighbor sneeze in front of your ornamental grasses, while your children play hide-and-seek in them without any problems?

It’s because every immune system is unique, like a fingerprint. Some people react excessively to ragweed pollen but are completely unaffected by pine pollen. Others panic at the sight of dust from ficus leaves but tolerate grasses perfectly well. And of course, since different types of pollen are suspended in the air and invisible, it’s impossible to know which one is responsible for your terrible sneezing fits!

Traveling Pollen vs. Sedentary Pollen

There are two main categories of plants when classified by their method of pollination:

1. Anemophilous plants (from the Greek word anemos, meaning “wind”): These plants rely on the wind to carry their pollen, which is transported by air currents. To maximize their chances of reproduction, they produce TONS of light pollen that can travel for miles. This is the case with ragweed, birch trees, grasses… and guess what? These are the plants that cause the most allergies! After all, their strategy is literally to send their pollen into your nostrils!

2. Entomophilous plants (from the Greek entomon, meaning “insect”): These plants rely on insects to transport their pollen. This pollen is heavier and stickier, and generally stays close to the plant unless a bee decides to carry it away. Roses, peonies, daisies… These colorful and fragrant flowers are less likely to cause allergies since their pollen does not fly through the air.

Now you understand why ragweed, the ultimate wind-pollinated plant, is so problematic? A single plant can produce up to a BILLION pollen grains per season, and it is DESIGNED to fly. It only takes ONE grain per cubic meter of air to trigger symptoms in a sensitive person. No wonder ragweed is the arch enemy of picnics!

Some Common Allergenic Plants

Some plants look completely harmless, but turn out to be real pests (for some people!) once they are introduced into our space. They don’t have thorns, don’t look threatening, and yet…! Here are some of our most common plants that could be responsible for your allergic reactions.

Ragweed

And then it’s a disaster for millions of people across North America! Ragweed is responsible for 50 to 75% of late-summer seasonal allergies, especially in eastern Canada and the U.S. Midwest and Northeast. In some cities and towns, you can even get fined for not removing it from your property! No wonder it’s often called “public enemy number one” for allergy sufferers.

Grasses

Grasses (or Poaceae, for purists), the herbaceous plants that make up our lawns and meadows, are the second leading cause of allergies after ragweed. Their pollen, released in June and July, causes rhinitis, watery eyes, and sometimes even asthma. And to think that we work so hard to grow perfect lawns without knowing that they are veritable allergen factories!

Birch

Birch trees may be iconic in our landscapes—but they’re also a major source of spring allergies. Their pollen, released in large amounts in April and May, is highly allergenic. In places like Quebec, Ontario, the northeastern U.S., and the Pacific Northwest, birch pollen can affect up to 15% of the population. If you live in a wooded area—like the Laurentians, New England, or the Great Lakes region—chances are you know someone who dreads the return of spring because of these trees. Larry even wrote an article about allergenic trees if you’d like to learn more about what’s blooming (and making you sneeze).

Ficus

Ficus plants, who would have thought it, your houseplants can also “attack” your immune system! The sap (not the pollen, this time!) of this pretty houseplant that everyone has in their living room contains proteins similar to those found in latex. If you are allergic to latex gloves, beware of ficus sap! The dust that accumulates on its leaves can also cause sneezing fits in sensitive people, especially in winter when our homes are less ventilated.

It is often difficult to identify the culprit behind our allergies, especially since you can react to several plants!

The Sneezing Calendar

In Canada, every season brings its own set of allergens. Here is a quick calendar to help you identify what makes you sneeze and/or anticipate critical periods:

April–May

It’s the season for birch trees and other trees with catkins. Willows, found near rivers and in wetlands, add their pollen to the mix, especially in the Laurentians and Mauricie regions. And let’s not forget the ash tree, a discreet but sneaky tree that is common in cities.. Even maple trees, emblematic of our forests, release a little pollen in the spring, although it is less aggressive. If your friends start canceling their spring visits to the cottage, you know why!

June-July

Grasses (timothy grass, bluegrass, etc.) turn your dream lawn into a nightmare for allergy sufferers. Their pollen, released in large quantities, causes rhinitis, watery eyes, and sometimes asthma, especially in agricultural regions. Phragmites, those giant reeds that colonize highway edges and lake shores, add to the problem with their light pollen. And watch out for mugwort (Artemisia vulgaris), a discreet herb that grows in vacant lots but is also sometimes cultivated for ornamental purposes. Its pollen, although less abundant than that of grasses, begins to circulate in July, causing sneezing in those who are sensitive to it. If your lakeside BBQ attracts guests who are sniffling, it’s not just the smell of sausages!

Mid-July to September

Ragweed steals the show with its highly allergenic pollen, turning picnics into sneezing fits for about one in four. But this queen of fields and roadsides isn’t alone! Amaranth, a discreet cousin found in gardens and vacant lots, also releases allergenic pollen starting in August.

And watch out for goldenrod (Solidago spp.) — while its bright yellow flowers get the blame, its heavy, insect-carried pollen is unlikely to trigger airborne allergies. That said, walking through a dense field of goldenrod can still cause irritation in sensitive individuals, especially through skin contact or in the presence of hidden ragweed nearby.

September–October

Mold gets involved! It settles on dead leaves and compost piles, turning your rake into a sneezing weapon. The spores, released on beautiful autumn days, aggravate rhinitis and asthma. And that’s not all! Stinging nettles, although known for their stinging hairs, can still release a little pollen at the end of the season.

It Itches, It Stings!

Tactile sensitivity to plants is something else entirely! It’s not a classic allergy (like those caused by pollen), but rather a skin reaction to direct contact with certain plants. And it varies greatly from person to person!

Did I mention brambles? Well, my partner’s arms turn red and swell up for hours after touching tomato stems and leaves! On the other hand, he can pick nettles without any problem. It’s really strange to see how different people react to the same scratches or toxins! But how do these topical reactions work?

Stinging Hairs

The stinging hairs of certain plants are the most obvious culprits. Stinging nettles are a perfect example: their tiny hollow hairs contain a cocktail of histamine, acetylcholine, and formic acid that, upon contact, break like tiny shards of glass and inject these irritating substances into your skin. The immediate burning sensation is universal—it’s a chemical defense mechanism of the plant, not an allergy—but some people react much more strongly and for longer than others.

Glandular Trichomes

Glandular trichomes are those little sticky hairs found on the stems and leaves of tomatoes, eggplants, and other Solanaceae. These hairs release defensive substances against insects, but our skin doesn’t all react to them in the same way. Some people may develop small blisters after coming into contact with them! And then they use that as an excuse to get someone else to pick the tomatoes… right, honey? That’s right, go play in the raspberry bushes while you wait!

Thorns and Barbs

The thorns and spines of brambles (appropriately enough), rose bushes, and other prickly plants can also cause very different reactions. Where some people only get a slight red mark that disappears within a few minutes, my skin develops red patches that itch for days. It’s not just the scratch: some thorns contain irritating substances that can exacerbate the reaction.

In short, skin reactions are a whole other way of “suffering” from nature. Fortunately, it’s much easier to identify the culprit than in the case of pollen, and it’s also easier to avoid exposure.

What makes you more sensitive to contact with one plant than another varies: for some people, it’s really an immune system reaction, while for others, the skin may be sensitive (sunburn, eczema, dry skin). We don’t all have the same skin either! Some people have thicker skin that is more resistant to injury, or have more body hair, which provides some protection.

Strategies for a Less Allergenic Garden

1. Choose insect-friendly plants for your flower beds: Opt for roses, echinacea, peonies, clematis, or ornamental cornflowers. Their heavy pollen stays on the plant and won’t tickle your guests’ nostrils.
2. Wear appropriate gloves and/or long sleeves when working with irritating plants: I know, I know, this is THE most useful tip on this list! You would never have thought of that on your own, right? Wash with soap if you do come into contact with nettles or other plants that cause a reaction.r.
3. Avoid wind-pollinated trees and grasses: Replace birch trees with ornamental maples or apple trees, which have low allergenic potential. And of course, hunt down ragweed without mercy!
4. Choose female plants: This is possible for dioecious species (which have separate male and female plants). Female plants do not produce pollen—they receive it!
5. Maintain your garden regularly: Mow your lawn often (but not TOO often!) to prevent grasses from flowering.
6. Create natural barriers: Plant dense hedges to block pollen from outside.
7. Avoid irritating plants where you spend time: It’s pretty logical, but rose bushes and stinging nettles may not be the best plants to put within a foot of your front door!
8. Health first: Bring your antihistamines with you, especially if you have increased sensitivity. You can never be too careful! You never know when you might arrive at your friends’ house and find that they’re growing ragweed without knowing it, because they think it looks pretty!

Strategies for a Less Allergenic Garden

I learned my lesson with my ragweed episode. Now I’m careful about what I let grow in my garden, not only for my visitors, but also out of respect for my neighbors. After all, pollen travels for miles! The irony is that allergenic plants aren’t trying to harm us—they’re just trying to reproduce. It’s not their fault that our immune systems go haywire!

Are you one of those people who dread pollen season or pruning roses? Share your experiences and tips in the comments!